Mobility of Toxic Elements in Crop and Agricultural Soil Treated with Municipal Sewage Sludge

The toxic metal absorption in radish crop and soil treated with sewage sludge in research plot in Allahabad Agricultural Institute -Deemed University, Allahabad have been studied to evaluate the absorption of toxic metal. Sewage sludge used in this study has high contents of both organic matter and nutrients (N, P and K) and none of the heavy metals were found over the maximum established limits. This soil is suitable for growing crops as none of the metals were absorbed above permissible limit. When the sludge was added to the soil, some of the physico-chemical parameters are modified which affects the absorption of toxic metals. When the sewage sludge was used with fertilizers it has given good response in respect of nutrient content and production. There was no phytotoxicity level on the plant growth treated with municipal sewage sludge, due to cumulative accumulation and also high bioavailability of metals; plant metal content exceeds safety food metal limits. It can be seen that heavy metals could be passed to higher levels in the course of time by successive applications of municipal sewage sludge of agronomic rates and thus it could be inevitable to suffer the irreversible problems of cumulative loading of trace elements and in any type of soil in long term effect. However, the agricultural use of this sludge should be well controlled, bearing in mind environmental criteria, because of the persistence of metals in the soil.